Superimposed image display device

Abstract

To provide a superimposed image display device enabling an occupant to clearly recognize a road to exit from among a plurality of roads.SOLUTION: When there is a guide object spot to be a guide object ahead in a traveling direction of a vehicle, a guidance object for guiding a route of the vehicle at the guide object spot is displayed. While displaying the guidance object, the guidance object is displayed in a size in accordance with an angle made by an entrance direction in which the vehicle enters a guidance junction along the route of the vehicle and an exit direction in which the vehicle exits from the guidance junction along the route of the vehicle, and the smaller the angle is, the smaller the guidance object is displayed.SELECTED DRAWING: Figure 11

Description

Technical Field

[0001] The present invention relates to a superimposed image display device for performing driving support of a vehicle.

Background Art

[0002] Conventionally, various means have been used as information providing means for providing various types of information for performing driving support of a vehicle, such as route guidance and warning of obstacles, to an occupant of the vehicle. For example, display on a liquid crystal display installed in the vehicle, voice output from a speaker, and the like. In recent years, as one of such information providing means, there is a device that provides information by displaying an image superimposed on the surrounding environment (scenery, real scene) of the occupant. For example, a head-up display, a windshield display, and a method of displaying an image superimposed on a captured image around the vehicle displayed on a liquid crystal display are applicable.

[0003] Here, when guiding a guidance target point to be guided to an occupant of a vehicle by displaying an image superimposed on the surrounding environment, it is effective to superimpose the superimposed image near the guidance target point. Examples of the guidance target point include a guidance branch point where the vehicle turns right or left, a ground feature (facility, signboard, etc.) serving as a landmark of the guidance branch point, an obstacle that needs to be alerted, and the like. For example, Japanese Patent Application Laid-Open No. 2021-39085 discloses a technique in which when a vehicle approaches within a guidance start distance (300 m for a general road) of a guidance branch point, a captured image of the front of the vehicle is displayed on a display, and a plurality of arrow images indicating the exit direction of the guidance branch point are displayed along the driving route of the vehicle included in the captured image.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] The technology described in the above Patent Document 1 indicates the exit direction of the vehicle at the guiding branch point according to the direction pointed by the image of the arrow. For example, if an image of an arrow pointing to the left is displayed, it indicates that the exit direction of the vehicle at the guiding branch point is to the left. However, among the branch points, there are also branch points where a plurality of roads are connected at a close angle. For example, even if an image 201 of an arrow pointing to the left is displayed at the guiding branch point as shown in FIG. 14, there is a problem that the passenger cannot determine which of the roads 202 and 203 to exit.

[0006] The present invention has been made to solve the above-described conventional problems, and even at a guiding branch point where a plurality of roads are connected at a close angle, it is possible to clearly allow the passenger to recognize the road to be exited from among the plurality of roads according to the size of the guiding object arranged along the vehicle's traveling route, and an object of the present invention is to provide a superimposed image display device.

Means for Solving the Problems

[0007] The superimposed image display device according to the present invention for achieving the above object is a superimposed image display device mounted on a vehicle, which superimposes and visually recognizes a guiding object for guiding information to a passenger of the vehicle on the scenery around the vehicle, and when there is a guiding branch point in front of the traveling direction of the vehicle, has an object display means for displaying the guiding object for guiding the traveling route of the vehicle at the guiding branch point along the traveling route of the vehicle. The guiding object includes a plurality of objects arranged at predetermined intervals along the path of the vehicle. The object display means When displaying the plurality of objects, displays according to the angle formed by the entry direction into the guiding branch point on the traveling route of the vehicle and the exit direction from the guiding branch point on the traveling route of the vehicle, and the smaller the angle, reduce the size of the plurality of objects step by step as the distance from the vehicle increases at a reduction rate Increase the reduction rate Note that the "scenery" includes not only the scenery actually visible from the vehicle (actual scene), but also an image obtained by imaging the scenery, an image reproducing the scenery, and the like.

Effects of the Invention

[0008] ​​According to the superimposed image display device of the present invention having the above configuration, when displaying a guide object that guides the vehicle route at a guide branch point along the vehicle route, the smaller the difference in the angle formed by the entry direction into the guide branch point and the exit direction from the guide branch point, As the distance from the vehicle increases guide object reduce the size more it is displayed, so that even at a guide branch point where a plurality of roads are connected at a close angle, it is possible to clearly make the passenger recognize the road to exit from among the plurality of roads.

Brief Description of the Drawings

[0009]

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Mode for Carrying Out the Invention

[0010] Hereinafter, a first embodiment and a second embodiment in which the superimposed image display device according to the present invention is embodied in a navigation device will be described in detail with reference to the drawings.

[0011] [First Embodiment] First, the schematic configuration of the navigation device 1 according to the first embodiment will be described with reference to FIG. 1. FIG. 1 is a block diagram showing the navigation device 1 according to the first embodiment.

[0012] As shown in FIG. 1, the navigation device 1 according to the first embodiment includes a current position detection unit 11 that detects the current position of the vehicle on which the navigation device 1 is mounted, a data recording unit 12 in which various data are recorded, a navigation ECU 13 that performs various arithmetic processes based on the input information, an operation unit 14 that receives operations from the user, a liquid crystal display 15 that displays a real-scene image obtained by imaging the front in the traveling direction for the user, a speaker 16 that outputs voice guidance regarding route guidance, a DVD drive 17 that reads a DVD which is a storage medium, and a communication module 18 that communicates with information centers such as a probe center and a VICS (registered trademark: Vehicle Information and Communication System) center. Further, the navigation device 1 is connected to a front camera 19 and various sensors installed in the vehicle on which the navigation device 1 is mounted via an in-vehicle network such as CAN.

[0013] Hereinafter, each component of the navigation device 1 will be described in order. The current position detection unit 11 consists of a GPS 21, a vehicle speed sensor 22, a steering sensor 23, a gyro sensor 24, etc., and is capable of detecting the current position, orientation, traveling speed of the vehicle, the current time, etc. Here, in particular, the vehicle speed sensor 22 is a sensor for detecting the moving distance and vehicle speed of the vehicle. It generates pulses according to the rotation of the driving wheels of the vehicle and outputs a pulse signal to the navigation ECU 13. Then, the navigation ECU 13 calculates the rotational speed and moving distance of the driving wheels by counting the generated pulses. Note that it is not necessary for the navigation device 1 to be equipped with all of the above four types of sensors, and the navigation device 1 may be configured to be equipped with only one or more types of these sensors.

[0014] Also, the data recording unit 12 includes an external storage device and a hard disk (not shown) as a recording medium, and a recording head (not shown) which is a driver for reading map information DB 31 and a predetermined program recorded on the hard disk and writing predetermined data to the hard disk. Note that the data recording unit 12 may be configured by a flash memory, a memory card, an optical disk such as a CD or a DVD instead of the hard disk. Also, the map information DB 31 may be stored in an external server, and the navigation device 1 may be configured to acquire it through communication.

[0015] Here, the map information DB 31 is, for example, a storage means in which link data 32 regarding roads (links), node data 33 regarding node points, branch point data 34 regarding branch points, point data regarding points such as facilities, map display data for displaying a map, search data for searching for a route, search data for searching for a point, etc. are stored.

[0016] In addition, as the link data 32, for each link constituting the road, data representing the width, gradient, cant, bank, road surface condition, number of lanes of the road to which the link belongs, locations where the number of lanes decreases, locations where the width narrows, level crossings, etc. are recorded. For corners, data representing the radius of curvature, intersections, T-junctions, entrances and exits of corners, etc. are recorded. For road attributes, data representing downhill roads, uphill roads, etc. are recorded. For road types, data representing highways and general roads (national roads, prefectural roads, small streets, etc.) are recorded respectively.

[0017] In addition, as the node data 33, coordinates (positions) of node points set at predetermined distances according to the radius of curvature, etc. for actual road branch points (including intersections, T-junctions, etc.) and each road, node attributes representing whether the node is a node corresponding to an intersection, a connection link number list which is a list of link numbers of links connected to the node, an adjacent node number list which is a list of node numbers of nodes adjacent to the node via a link, data regarding the height (altitude) of each node point, etc. are recorded.

[0018] In addition, as the branch point data 34, the intersection name of the branch point, corresponding node information identifying the nodes forming the branch point, connection link information identifying the links connected to the branch point, aspect names corresponding to the links connected to the branch point, information specifying the shape of the branch point, etc. are stored. Also, structures that can serve as landmarks when guiding right or left turns at the branch point are also stored.

[0019] In addition, as the information specifying the shape of the branch point included in the branch point data 34, in particular, in addition to the number of roads connected to the intersection, information specifying in which direction each road is connected to the intersection is included. For example, for an intersection where five roads 51 to 55 are connected as shown in FIG. 2, the angles θ1 of road 51, θ2 of road 52, θ3 of road 53, θ4 of road 54, and θ5 of road 55 are respectively stored with respect to one direction (for example, the north direction).

[0020] On the one hand, the navigation ECU (Electronic Control Unit) 13 is an electronic control unit that controls the entire navigation device 1. It includes a CPU 41 as an arithmetic unit and a control unit, a RAM 42 that is used as a working memory when the CPU 41 performs various arithmetic processes and stores route data, etc. when a route is searched, a ROM 43 that records, in addition to control programs, a driving support processing program (Figure 3) described later, and an internal storage device such as a flash memory 44 that stores the program read from the ROM 43. The navigation ECU 13 has various means as processing algorithms. For example, the object display means displays a guide object that guides the vehicle's route at a guide branch point along the vehicle's route when there is a guide branch point ahead in the traveling direction of the vehicle.

[0021] The operation unit 14 is operated when inputting a departure point as the start point of travel and a destination as the end point of travel, etc., and has a plurality of operation switches (not shown) such as various keys and buttons. Then, the navigation ECU 13 performs control based on the switch signals output when each switch is pressed, etc., to execute corresponding various operations. The operation unit 14 may be configured to have a touch panel provided on the front surface of the liquid crystal display 15. It may also be configured to have a microphone and a voice recognition device.

[0022] In addition, on the liquid crystal display 15, a map image including roads, traffic information, operation guidance, operation menus, key guidance, a guided route from the departure point to the destination, guidance information along the guided route, news, weather forecasts, time, emails, TV programs, etc. are displayed. In particular, in the first embodiment, when the vehicle approaches a guide branch point, the liquid crystal display 15 displays an imaging image captured by the front camera 19, that is, a view (real scene image) of the vehicle's surroundings (especially in front of the vehicle) at the current time, and further superimposes and displays a guide object on the view as needed.

[0023] Here, as the guidance objects displayed superimposed on the scenery, there is information related to the vehicle and various types of information used for assisting the driving of the occupants. For example, warnings for objects to be warned against by the occupants (other vehicles, pedestrians, guidance signs), guidance routes set in the navigation device 1 and guidance information based on the guidance routes (arrows indicating the right / left turn directions, icons indicating landmarks of guidance branch points, distances to guidance branch points, etc.), warnings displayed on the road surface (collision warning, speed limit, etc.), lane dividing lines of the lane on which the vehicle is traveling, current vehicle speed, shift position, remaining energy, advertisement images, facility information, guidance signs, map images, traffic information, news, weather forecasts, time, screens of connected smartphones, and the like. In addition, in the first embodiment described below, the guidance object is guidance information for guiding at a guidance branch point in front of the traveling direction of the vehicle. More specifically, it is an arrow indicating the exit direction of the guidance branch point, a plurality of arrows arranged along the future route of the vehicle at the guidance branch point, and the like.

[0024] In addition, the speaker 16 outputs voice guidance for guiding travel along the guidance route and guidance of traffic information based on an instruction from the navigation ECU 13.

[0025] In addition, the DVD drive 17 is a drive capable of reading data recorded on recording media such as DVDs and CDs. Then, based on the read data, music and video are played back, the map information DB 31 is updated, and the like. Note that a card slot for reading and writing memory cards may be provided instead of the DVD drive 17.

[0026] In addition, the communication module 18 is a communication device for receiving traffic information composed of various information such as traffic jam information, regulation information, and traffic accident information transmitted from a traffic information center, for example, a VICS center or a probe center. For example, a mobile phone or a DCM corresponds to this.

[0027] The front camera 19 is an imaging device having a camera using a solid-state imaging device such as a CCD, and is installed, for example, on the back side of the rearview mirror or the front bumper with the optical axis direction facing forward in the vehicle traveling direction. Then, the captured image captured by the front camera 19 is displayed on the liquid crystal display 15 as a view (real scene image) around the vehicle (especially in front of the vehicle) as described above.

[0028] Subsequently, the travel support processing program executed by the navigation ECU 13 in the navigation device 1 having the above configuration will be described with reference to FIG. 3. FIG. 3 is a flowchart of the travel support processing program according to the first embodiment. Here, the travel support processing program is executed after the ACC power supply (accessory power supply) of the vehicle is turned on, and is a program for performing travel support of the vehicle by allowing a guidance object superimposed on the view around the vehicle displayed on the liquid crystal display 15 to be visually recognized. Note that the programs shown in the flowcharts in FIGS. 3 and 5 below are stored in the RAM 42 and the ROM 43 provided in the navigation device 1 and are executed by the CPU 41.

[0029] In the following description, as an example of vehicle driving support using a guidance object, an example of performing vehicle driving guidance along a guidance route set in the navigation device 1 will be described. Further, the guidance object to be displayed is guidance information for performing guidance at a guidance branch point in front of the traveling direction of the vehicle. In particular, the process in the case of displaying, as the guidance object, an arrow indicating the exit direction of the guidance branch point and a plurality of arrows arranged along the future route of the vehicle at the guidance branch point will be described as an example. However, in the navigation device 1, it is also possible to perform guidance and information provision other than the above driving support using the guidance object. Further, the guidance object to be displayed may be information other than the above arrow. For example, as the guidance object, a warning to an object (other vehicle, pedestrian, guidance sign) to be warned to the occupant, a warning displayed on the road surface (collision warning, speed limit, etc.), the distance to the next guidance branch point, the current vehicle speed, the shift position, the remaining energy, an advertisement image, facility information, a guidance sign, a map image, traffic information, news, weather forecast, time, the screen of the connected smartphone, etc. can also be displayed.

[0030] First, in the driving support processing program, in step (hereinafter abbreviated as S) 1, the CPU 41 specifies the current position of the vehicle based on the detection result of the current position detection unit 11 and the map information. In addition, when specifying the current position of the vehicle, map matching processing for matching the current position of the vehicle with the map information is also performed. Then, the guidance route set in the navigation device 1 is read out, and the distance from the specified current position of the vehicle to the next guidance branch point along the guidance route is calculated. In addition, the guidance branch point is a branch point (intersection) that is the target of guidance such as a right / left turn instruction when the navigation device 1 performs driving guidance according to the guidance route set in the navigation device 1. In addition, a branch point (complicated intersection) that does not make a right / left turn but has a special shape also corresponds to the guidance branch point.

[0031] Next, in S2, the CPU 41 determines whether the distance to the next guidance branch point calculated in S1 is less than a predetermined guidance start distance. The guidance start distance is determined according to the road type of the road on which the vehicle travels. For example, on a highway, it is 500 m, and on a general road, it is 200 m, which is shorter than that on a highway. However, the guidance start distance may not be a fixed value but a variable value. For example, when there is another branch point within 200 m before the guidance branch point on a general road, it may be the distance from the guidance branch point to the other branch point.

[0032] And when it is determined that the distance to the next guidance branch point calculated in S1 is less than the guidance start distance (S2: YES), the process proceeds to S3. On the contrary, when it is determined that the distance to the next guidance branch point calculated in S1 is not less than the guidance start distance (S2: NO), the process returns to S1.

[0033] In S3, the CPU 41 acquires the coordinates of the point to be guided by the guidance object, that is, the point where the guidance object should be superimposed (placed) (hereinafter referred to as the guidance point). In the first embodiment, since the right and left turn guidance of the guidance branch point is performed using the guidance object, the guidance point corresponds to the guidance branch point (more specifically, above the road surface of the guidance branch point separated by a predetermined distance), and therefore the coordinates of the guidance point correspond to the coordinates of the guidance branch point. The coordinates of the guidance branch point shall be specified from the map information possessed by the navigation device 1, but may also be specified by performing image recognition processing on the image captured by the front camera 19.

[0034] Next, in S4, the CPU 41 performs guidance object display position determination processing (Fig. 5) described below. The guidance object display position determination processing is a process of specifically determining the size, shape, and position (range) of the guidance object to be displayed on the liquid crystal display 15 based on the current position of the vehicle and the coordinates of the guidance point acquired in S3. Note that the size, shape, and position of the guidance object determined in S4 are conditions for superimposing the guidance object on a guidance point in the scenery or its vicinity and allowing the passenger to visually recognize it. However, depending on the current position of the vehicle and the type of guidance object, there may be cases where the guidance object is superimposed and visually recognized outside the guidance point in the scenery or its vicinity.

[0035] Subsequently, in S5, the CPU 41 generates an image of the guidance object with the size and shape determined in S4, and further transmits a control signal to the liquid crystal display 15 to draw the generated image of the guidance object on the liquid crystal display 15 at the position (range) determined in S4. Note that the liquid crystal display 15 displays an imaging image captured in advance by the front camera 19 before the distance from the vehicle to the guidance branch point becomes less than the guidance start distance, that is, the scenery (real scene image) around the vehicle at the current time (especially in front of the vehicle). As a result, it becomes possible for the passenger of the vehicle to visually recognize the guidance object superimposed on the scenery.

[0036] Fig. 4 is a diagram showing an example of the travel guidance screen 61 displayed on the liquid crystal display 15 in S5. As shown in Fig. 4, the liquid crystal display 15 displays the scenery 62 in front of the vehicle at the current time captured by the front camera 19. Then, an image of the guidance object is displayed superimposed on the scenery 62 in front of the vehicle.

[0037] Here, in the first embodiment, there are multiple types of guiding objects used for guiding, and one or more types of guiding objects selected according to the guiding content and the current situation are displayed. Also, there may be cases where multiple types of guiding objects are simultaneously displayed as display targets. For example, the example shown in FIG. 4 is an example of a driving guidance screen 61 displayed when the current position of the vehicle approaches a guiding intersection by a predetermined distance (for example, 40 m). An image 63 of a first guiding object composed of arrows indicating the exit direction of the guiding intersection and the intersection name, and an image 64 of a second guiding object composed of a plurality of arrows arranged along the future route of the vehicle at the guiding intersection are simultaneously displayed.

[0038] Regarding the image 63 of the first guiding object, it is superimposed and displayed at a position a predetermined distance (for example, 3 m) above the road surface of the guiding intersection within the scenery 62 (a position higher than the line of sight of the vehicle occupants).

[0039] On the other hand, regarding the image 64 of the second guiding object, it is superimposed and displayed at a position a predetermined distance (for example, 1 m) above the road surface of the guiding intersection within the scenery 62 (the position of the line of sight of the vehicle occupants). Note that the image 64 of the second guiding object includes images of a plurality of arrow-shaped objects, and the images of the plurality of objects are displayed at predetermined intervals along the future route of the vehicle at the guiding intersection. The direction of each arrow indicates the traveling direction of the vehicle at the guiding intersection. Also, regarding the image 64 of the second guiding object, as will be described later, it is displayed in a size corresponding to the angle formed between the entry direction into the guiding intersection on the vehicle's route and the exit direction from the guiding intersection on the vehicle's route. More specifically, the smaller the angle formed between the entry direction and the exit direction (that is, the closer the exit direction is to going straight with respect to the entry direction), the smaller the image 64 of the second guiding object located at a position farther from the vehicle is displayed. Details will be described later.

[0040] In addition to the arrows indicating the exit direction and intersection name of the vehicle guidance branch point and the arrows indicating the future route of the vehicle at the guidance branch point described above, an image indicating the distance to the guidance branch point may also be superimposed on the scenery and displayed. The position where the image indicating the distance to the guidance branch point is superimposed is, for example, the road surface closest to the front of the vehicle, and is displayed while the distance from the vehicle to the guidance branch point is within a predetermined distance range (for example, 200 m to 60 m on a general road).

[0041] Thereafter, in S6, the CPU 41 determines whether the vehicle has passed through the guidance branch point. For example, it is determined based on the current position of the vehicle detected by the current position detection unit 11 and the map information.

[0042] When it is determined that the vehicle has passed through the guidance branch point (S6: YES), a control signal is transmitted to the liquid crystal display 15 to make the guidance object displayed on the liquid crystal display 15 non-displayed (S7). Note that the captured image captured by the front camera 19, that is, the scenery (real scene image) around the vehicle at the current time (especially in front of the vehicle) is continuously displayed for a certain period of time and then switched to the display of the map image.

[0043] On the other hand, when it is determined that the vehicle has not passed through the guidance branch point (S6: NO), the process returns to S4 and the display of the guidance object is continued.

[0044] Next, the sub-process of the guidance object display position determination process executed in S4 will be described with reference to FIG. 5. FIG. 5 is a flowchart of the sub-process program of the guidance object display position determination process.

[0045] First, in S11, the CPU 41 generates a three-dimensional space corresponding to the vicinity of the current position of the vehicle (especially the front in the vehicle traveling direction). Note that in the three-dimensional space, in addition to the road, buildings, road signs, etc. may be modeled, or only the road may be modeled. Alternatively, it may be a mere blank three-dimensional space with only the ground without modeling the road. Also, the three-dimensional space may be stored in the map information DB 31 in advance as three-dimensional map information, and in S11, the three-dimensional map information around the corresponding own vehicle position may be read from the map information DB 31. Also, a three-dimensional space may be generated based on the image captured by the front camera 19. For example, by performing point cloud matching on the captured image captured by the front camera 19, it is possible to detect roads and structures around the road and generate a three-dimensional space.

[0046] Also, in S11, the CPU 41 specifies the current position and orientation of the own vehicle in the generated three-dimensional space based on the parameters detected by the current position detection unit 11. In particular, the position of the front camera 19 installed in the vehicle is set as the current position of the own vehicle, and the optical axis direction of the front camera 19 is set as the orientation of the own vehicle. Note that the position of the front camera 19 also corresponds to the position of the vehicle occupant, and the optical axis direction of the front camera 19 also corresponds to the line-of-sight direction of the vehicle occupant. Also, in S11, the position of the guiding branch point in front of the vehicle traveling direction in the generated three-dimensional space is also specified.

[0047] Next, in S12, the CPU 41 generates a first guiding object 65 as a guiding object to be displayed. Note that the first guiding object 65 is a single arrow indicating the exit direction of the guiding branch point as shown in FIG. 6. The size is set to 2 m in length and 4 m in width. Also, the intersection name is drawn inside the arrow. Also, the guiding object is a two-dimensional polygon and basically has no thickness. However, it may be a three-dimensional polygon with thickness. Also, the shape of the first guiding object 65 generated in S12 can be appropriately changed, and any shape other than an arrow may be used as long as it can indicate the exit direction at the guiding branch point.

[0048] Furthermore, in S12, the CPU 41 arranges the generated first guide object 65 with respect to the three-dimensional space generated in S11. Incidentally, the position where the first guide object 65 is arranged with respect to the three-dimensional space is located near the center of the guide branch point 66 as shown in FIG. 7, and is arranged such that the tip of the arrow faces in the exit direction of the guide branch point. Therefore, when turning right at the guide branch point, it becomes an arrow pointing to the right as seen from the vehicle, and when turning left at the guide branch point, it becomes an arrow pointing to the left as seen from the vehicle. Incidentally, when turning right or left other than in the right angle direction, it becomes an arrow inclined in the diagonal direction. Also, the height at which it is arranged is a position a predetermined distance (for example, 3 m) above the road surface (a position higher than the line of sight of the vehicle occupant). Then, the process proceeds to S13.

[0049] In S13, the CPU 41 reads out the branch point data 34 stored in the map information and the guide route set in the navigation device 1, and specifies the approach road on which the vehicle enters the guide branch point and the exit road on which the vehicle exits from the guide branch point when the vehicle travels along the guide route.

[0050] Next, in S14, the CPU 41 calculates the angle (hereinafter referred to as the exit angle) formed by the approach direction in which the vehicle enters the guide branch point in the vehicle's course and the exit direction in which the vehicle exits from the guide branch point in the vehicle's course. Incidentally, the "approach direction" is the traveling direction of the vehicle on the approach road, and the "exit direction" is the traveling direction of the vehicle on the exit road. That is, as shown in FIG. 8, when the vehicle's course in the guide route enters the guide branch point 66 from the approach road 71 and exits from the diagonally forward right exit road 72, the exit angle is the angle θ between the line extending the approach road 71 and the exit road 72. Incidentally, the branch point data 34 stores the connection angles of the respective roads connected to the branch point as shown in FIG. 2, and the above-mentioned exit angle is calculated using the branch point data 34.

[0051] Subsequently, in S15, the CPU 41 calculates the minimum magnification of the second guide object 70 based on the exit angle calculated in S14. Specifically, it is calculated by the following formula (1). Minimum magnification = 1 - (90 degrees - exit angle) × 0.0075 ··· (1)

[0052] Therefore, when the exit angle is 90 degrees, that is, when the intersection where the vehicle goes straight is the guiding branch point, the minimum magnification is "1". And the smaller the exit angle becomes (that is, the closer the exit direction is to straight ahead with respect to the entry direction), the smaller the minimum magnification becomes. In addition, when the exit angle is greater than 90 degrees, the calculation is performed by regarding the exit angle as 90 degrees, and the minimum magnification is set to "1".

[0053] In addition, the second guiding object 70 includes a plurality of substantially triangular objects arranged along the vehicle's path as described later. When the exit angle is less than 90 degrees (that is, the minimum magnification is less than "1"), the smaller-sized objects are arranged at positions farther from the vehicle. And the minimum magnification calculated in S15 is the size ratio of the object arranged at the position farthest from the vehicle (that is, the smallest object) to the object arranged at the position closest to the vehicle (that is, the largest object) among the plurality of objects included in the second guiding object 70. In addition, when the minimum magnification is "1", since all the objects included in the second guiding object 70 have the same size, the processing of S16 below is omitted.

[0054] In S16, the CPU 41 individually determines the magnification of each object included in the second guidance object 70 based on the minimum magnification calculated in S15. Note that the "magnification" is the size ratio of each object to the object arranged at the position closest to the vehicle (i.e., the largest object). Specifically, the magnification of each object is set so that the farther the object is arranged from the vehicle at a certain ratio, the smaller the size of the object becomes, and the magnification of the object arranged at the farthest position from the vehicle becomes the minimum magnification. For example, as shown in FIG. 9, when the minimum magnification is 0.73 and there are 10 objects, the magnifications of the objects are "1", "0.97", "0.94", "0.91", "0.88", "0.85", "0.82", "0.79", "0.76", "0.73 (minimum magnification)" in order from the closest to the vehicle.

[0055] Subsequently, in S17, the CPU 41 generates the second guidance object 70 as the guidance object to be displayed. Note that the second guidance object 70 is a plurality of arrows having an isosceles triangle shape indicating the vehicle's route at the guidance branch point, as shown in FIG. 9. The size is set with a reference size of 2 m in length and 2 m in width. When the exit angle is 90 degrees or more (i.e., the minimum magnification is "1"), all the arrows are set to the above reference size, while when the exit angle is less than 90 degrees (i.e., the minimum magnification is less than "1"), the arrow arranged at the position closest to the vehicle is set to the reference size, and for the other arrows, the size is the reference size multiplied by the magnification calculated in S16. Also, the guidance object is a two-dimensional polygon and basically has no thickness. However, it may be a three-dimensional polygon with thickness. Further, the shape of the second guidance object 70 generated in S17 can be appropriately changed, and any shape other than an arrow may be used as long as it can indicate the vehicle's route at the guidance branch point.

[0056] Furthermore, in S17, the CPU 41 arranges the generated second guiding object 70 in the three-dimensional space generated in S11. Incidentally, the positions where the second guiding object 70 is arranged in the three-dimensional space are arranged at predetermined intervals (for example, intervals of 1 m) along the vehicle's route at the guiding branch point 66 as shown in FIG. 10. More specifically, they are arranged at predetermined intervals in an arc shape from the vehicle's entry road to the exit road when passing through the guiding branch point. The positions of the entry road and the exit road in the three-dimensional space are specified from map information and the vehicle's guiding route. Also, the direction of each arrow is set to the direction indicating the vehicle's traveling direction at the guiding branch point. The number and arrangement interval of the second guiding objects 70 can be set as appropriate. Incidentally, it is desirable to arrange the second guiding object 70 closer to the outside than the center (for example, 1 / 2 lane closer to the outside) rather than at the center of the vehicle's route in order to improve the visibility for the passengers. Also, the height at which it is arranged is set to a position a predetermined distance (for example, 1 m) above the road surface (the position of the vehicle passengers' line of sight). Then, the process proceeds to S18.

[0057] In S18, the CPU 41 stores, as the size and shape of the guiding object to be displayed by the liquid crystal display 15, the size and shape of the first guiding object 65 and the second guiding object 70 that can be visually recognized when looking in the traveling direction of the vehicle from the current position of the vehicle and the position at the height of the front camera 19 in the three-dimensional space where the first guiding object 65 and the second guiding object 70 are arranged in S12 and S17. Here, the size and shape of the guiding object stored in S18 are the size and shape of the first guiding object 65 and the second guiding object 70 that can be visually recognized when the first guiding object 65 and the second guiding object 70 arranged in the three-dimensional space are visually recognized from the viewpoint of the current vehicle (more precisely, the front camera 19).

[0058] After that, in S19, the CPU 41 estimates the position of the guidance bifurcation point within the scenery 62 displayed on the liquid crystal display 15 based on the current position of the vehicle in the three-dimensional space generated in S11 and the position of the guidance bifurcation point, and determines the position where the first guidance object 65 is to be displayed on the liquid crystal display 15 at the center of the estimated position of the guidance bifurcation point and at a position a predetermined distance (e.g., 3 m) above the road surface.

[0059] Furthermore, in S19, the CPU 41 estimates the position of the guidance bifurcation point within the scenery 62 displayed on the liquid crystal display 15 based on the current position of the vehicle in the three-dimensional space generated in S11 and the position of the guidance bifurcation point, and determines the position where the second guidance object 70 is to be displayed on the liquid crystal display 15 in an arrangement along the vehicle's route at the guidance bifurcation point shown in FIG. 10 with respect to the estimated position of the guidance bifurcation point and at a position a predetermined distance (e.g., 1 m) above the road surface.

[0060] After that, the process proceeds to S5, where an image of the guidance object with the size and shape determined in S18 is generated, and a control signal is further transmitted to the liquid crystal display 15 to draw the generated image of the guidance object at the position (range) determined in S19 on the liquid crystal display 15.

[0061] As a result, the driving guidance screen 61 displayed on the liquid crystal display 15 as the vehicle travels becomes a screen as shown in FIG. 11. Here, the image 64 of the second guidance object is composed of a plurality of substantially triangular images and is visually recognized in a state of being arranged along the vehicle's route at the guidance branch point. Thereby, it suggests to the passenger the future route of the vehicle at the guidance branch point ahead in the traveling direction. Further, the size of the image 64 of the second guidance object changes according to the angle (exit angle) formed by the entry direction into the guidance branch point on the vehicle's route and the exit direction from the guidance branch point on the vehicle's route as described above, and the size of the image 64 of the second guidance object makes the vehicle's route (more specifically, the road to exit at the guidance branch point) at the guidance branch point clearer. For example, as shown in FIG. 11, the image 64 of the second guidance object is displayed with its size gradually changed so that the object located farther from the vehicle becomes smaller. However, compared with the case where the exit angle is 90 degrees as shown in FIG. 11, when the exit angle is less than 90 degrees, the object located farther from the vehicle is displayed smaller. Incidentally, when the exit angle is 90 degrees, the size of each object arranged as described above is the same regardless of the distance from the vehicle, but the size of the image of the object to be displayed is the size visually recognized from the current position of the vehicle (S18), so the object arranged farther away is displayed smaller than the object arranged in the foreground. When the exit angle is less than 90 degrees, the size of the object itself arranged as described above becomes smaller as the object is located farther from the vehicle, and since it is arranged even farther away, it is displayed even smaller. As a result, when the size of the object located farther away suddenly becomes smaller compared to the foreground for the passenger, it becomes possible to visually grasp that the road to exit where the object is arranged is deeper in the distance. Therefore, even at a guidance branch point where a plurality of roads are connected at a close angle, it becomes possible to clearly make the passenger recognize the road to exit from among the plurality of roads.

[0062] After the vehicle enters the guiding intersection, as the vehicle passes through the guiding intersection, the images 63 and 64 of the guiding object gradually become larger. Also, as the vehicle moves, the images of the guiding objects located behind the current position of the vehicle become non-displayed in order, and at the timing when the vehicle completes passing through the guiding intersection, the images 63 and 64 of the guiding object disappear from the liquid crystal display 15 (S7).

[0063] As described in detail above, according to the navigation device 1 according to the first embodiment and the computer program executed by the navigation device 1, when there is a guiding target point to be guided in front of the traveling direction of the vehicle, a guiding object for guiding the route of the vehicle at the guiding target point is displayed (S5). On the other hand, when displaying the guiding object, the guiding object is displayed in a size corresponding to the angle formed by the entering direction into the guiding intersection on the vehicle's route and the exiting direction from the guiding intersection on the vehicle's route, and the smaller the angle, the smaller the guiding object is displayed (S15 to S17). Therefore, even at a guiding intersection where a plurality of roads are connected at a close angle, it is possible to clearly make the passenger recognize the road to exit from among the plurality of roads. In addition, since the guiding object includes a plurality of objects arranged at predetermined intervals along the vehicle's route, it is possible to clearly make the passenger recognize the road to exit by the arrangement of the plurality of objects. Also, among the plurality of objects, the size of the object located at the position farthest from the vehicle is determined according to the angle formed by the entering direction and the exiting direction, and the plurality of objects are displayed with their sizes changed step by step so that the object located farther from the vehicle becomes smaller. Therefore, it is possible for the passenger to visually grasp the road to exit by the displacement of the sizes of the objects arranged along the route. For example, if the size of the object located farther away suddenly becomes smaller compared to the object in the foreground, it can be grasped that the road where the object is arranged to exit is deeper in the distance. In addition, when there is a guiding bifurcation point within a predetermined distance in front of the traveling direction of the vehicle, a guiding object for guiding the traveling route of the vehicle at the guiding bifurcation point is displayed, so that the driver can clearly recognize the road to exit for the guiding bifurcation point in front of the vehicle. Further, when the angle formed by the entry direction and the exit direction is 90 degrees or less, the guiding object is displayed in a size corresponding to the angle, and when the angle formed by the entry direction and the exit direction is greater than 90 degrees, the guiding object is displayed in a size when the angle is 90 degrees. Therefore, it is possible to prevent the traveling route of the vehicle from being difficult to understand due to the reversal of the sizes of the object located near the vehicle and the object located far away.

[0064] [Second Embodiment] Next, the superimposed image display device according to the second embodiment will be described with reference to FIGS. 12 and 13. In the following description, the same reference numerals as those of the superimposed image display device according to the first embodiment in FIGS. 1 to 11 indicate the same or corresponding parts as those of the superimposed image display device according to the first embodiment.

[0065] The schematic configuration of the superimposed image display device according to this second embodiment is substantially the same as that of the superimposed image display device according to the first embodiment. Also, various control processes are substantially the same as those of the superimposed image display device according to the first embodiment. However, the superimposed image display device according to the first embodiment displays the captured image captured by the front camera 19 on the liquid crystal display 15 of the navigation device 1, and further displays a guiding object on the liquid crystal display 15, thereby superimposing and displaying the guiding object on the scenery around the vehicle. In contrast, the superimposed image display device according to the second embodiment is different in that it uses a head-up display system as a means for displaying an image superimposed on the scenery around the vehicle.

[0066] The schematic configuration of the superimposed image display device according to the second embodiment will be described below with reference to FIG. 12. FIG. 12 is a schematic configuration diagram of the superimposed image display device 101 according to the second embodiment. As shown in FIG. 12, the superimposed image display device 101 basically includes a navigation device 103 mounted on the vehicle 102 and a front display 104 also mounted on the vehicle 102 and connected to the navigation device 103. Note that the front display 104 functions as a head-up display together with the front windshield 105 of the vehicle 102, and serves as an information providing means for providing various information to the occupant 106 of the vehicle 102.

[0067] Here, the front display 104 is a liquid crystal display installed inside the dashboard 107 of the vehicle 102 and having a function of displaying an image on an image display surface provided on the front surface. As the backlight, for example, a CCFL (cold cathode tube) or a white LED is used. Note that as the front display 104, in addition to a liquid crystal display, an organic EL display or a combination of a liquid crystal projector and a screen may be used.

[0068] Then, the front display 104 functions as a head-up display together with the front windshield 105 of the vehicle 102, and is configured to reflect the image output from the front display 104 on the front windshield 105 in front of the driver's seat so that the occupant 106 of the vehicle 102 can visually recognize it. Note that the front display 104 displays a guidance object as necessary. In the second embodiment described below, the guidance object is guidance information for guiding at a guidance branch point in front of the vehicle traveling direction, similar to the first embodiment. More specifically, it is an arrow indicating the exit direction of the guidance branch point, a plurality of arrows arranged along the future route of the vehicle at the guidance branch point, and the like.

[0069] Also, when the front glass 105 reflects the image displayed on the front display 104 and the occupant 106 visually recognizes it, the image displayed on the front display 104 is visually recognized as a virtual image 110 at a position far away from the front glass 105, rather than at the position of the front glass 105. Further, the virtual image 110 is configured to be displayed superimposed on the surrounding environment (scenery, real scene) in front of the vehicle, and can be displayed superimposed on, for example, any object located in front of the vehicle (road surface, building, object to be warned, etc.).

[0070] Here, the position where the virtual image 110 is generated, more specifically, the distance (hereinafter referred to as the imaging distance) L from the occupant 106 to the virtual image 110, is determined by the position of the front display 104. For example, the imaging distance L is determined by the distance (optical path length) along the optical path from the position where the image is displayed on the front display 104 to the front glass 105. For example, the optical path length is set so that the imaging distance L is 1.5 m.

[0071] In addition, a front camera 111 is installed above the front bumper of the vehicle or behind the rearview mirror. The front camera 111 is an imaging device having a camera using a solid-state imaging device such as a CCD, and is installed with the optical axis direction facing forward in the traveling direction of the vehicle. Then, by performing image processing on the captured image captured by the front camera 111, the situation of the front environment (i.e., the environment on which the virtual image 110 is superimposed) visually recognized by the occupant 106 through the front glass is detected. Note that a sensor such as a millimeter-wave radar may be used instead of the front camera 111.

[0072] In addition, an in-vehicle camera 112 is installed on the upper surface of the instrument panel of the vehicle. The in-vehicle camera 112 is an imaging device having a camera using a solid-state imaging device such as a CCD, and is installed with its optical axis direction facing the driver's seat. A range where the face of a passenger is generally expected to be located inside the vehicle is set as a detection range (imaging range of the in-vehicle camera 112), and the face of the passenger 106 sitting in the driver's seat is imaged. Then, by performing image processing on the captured image captured by the in-vehicle camera 112, the position (line-of-sight starting point) and line-of-sight direction of the passenger 106's eyes are detected.

[0073] Then, in S5 of the above-described driving support processing program (FIG. 3), the superimposed image display device according to the second embodiment displays an image 120 of a guidance object on the front display 104 as shown in FIG. 13. As a result, when the passenger in the vehicle visually recognizes the image 120 of the guidance object displayed on the front display 104 as shown in FIG. 13, a virtual image 121 of the image 120 of the guidance object is visually recognized superimposed on the scenery through the front glass 105.

[0074] Thereby, similar to the superimposed image display device according to the first embodiment, the position of the guidance branch point to be turned right or left and the exit direction at the guidance branch point can be accurately grasped. In addition, in the superimposed image display device according to the second embodiment, in the guidance object display position determination process of S4, the size, shape of the guidance object to be displayed on the front display 104, and the position (range) where the guidance object is displayed are determined. Further, it is desirable that the current position and orientation of the host vehicle specified in the three-dimensional space in S11 be the position of the passenger in the vehicle and the line-of-sight direction of the passenger detected using the in-vehicle camera 112.

[0075] Note that the present invention is not limited to the above-described embodiments, and it goes without saying that various improvements and modifications are possible without departing from the gist of the present invention. For example, as a means of displaying an image superimposed on the scenery around the vehicle, in the first embodiment, the liquid crystal display 15 on which the real-scene image is displayed is used, and in the second embodiment, a head-up display system is used. However, a windshield display (WSD) that displays an image on the front glass may also be used. In the WSD, an image may be displayed from a projector using the front glass as a screen, or the front glass may be used as a transmissive liquid crystal display. The image displayed on the front glass by the WSD becomes an image superimposed on the scenery around the vehicle.

[0076] Also, in the first and second embodiments, the guiding object is the first guiding object 65 which is an arrow indicating the exit direction of the vehicle at a guiding branch point in front of the traveling direction of the vehicle, and the second guiding object 70 which is an image of a plurality of arrows indicating the route of the vehicle at the guiding branch point. However, only the second guiding object 70 may be used. Also, the second guiding object 70 does not necessarily have to be a plurality of arrows, and may be a single long arrow or a line segment as long as it is arranged along the route of the vehicle. Also, in the case where the second guiding object 70 is a single arrow or a line segment, it is generated as an object in which the width of the arrow or the line segment is gradually decreased as it is located farther from the vehicle according to the magnification calculated in the above S15 and S16.

[0077] Also, in the first embodiment, a real-scene image or a guiding object captured by the front camera 19 is displayed on the liquid crystal display 15 of the navigation device 1. However, as a display for displaying the real-scene image or the guiding object, any display arranged inside the vehicle may be used as long as it is a display other than the liquid crystal display 15.

[0078] In the second embodiment, a virtual image is generated in front of the front windshield 105 of the vehicle 102 by the front display 104. However, a configuration in which a virtual image is generated in front of a window other than the front windshield 105 may also be used. Further, the object for reflecting the video by the front display 104 may be a visor (combiner) installed around the front windshield 105 instead of the front windshield 105 itself.

[0079] In the first and second embodiments, the navigation ECU 13 of the navigation device 1 executes the processing of the driving support processing program (Fig. 3). However, the execution entity can be appropriately changed. For example, a configuration in which the control unit of the liquid crystal display 15, the vehicle control ECU, or other in-vehicle devices execute the processing may also be used.

Description of Reference Numerals

[0080] 1... Navigation device, 15... Liquid crystal display, 19... Front camera, 41... CPU, 42... RAM, 43... ROM, 61... Driving guidance screen, 62... Landscape, 63... Image of the first guidance object, 64... Image of the second guidance object, 65... First guidance object, 66... Guidance branch point, 70... Second guidance object

Claims

1. A superimposed image display device mounted on a vehicle for visually superimposing a guiding object that guides information to an occupant of the vehicle on a landscape around the vehicle, having object display means for displaying the guiding object that guides the vehicle route at a guiding branch point along the vehicle route when there is a guiding branch point ahead in the traveling direction of the vehicle, wherein the guiding object includes a plurality of objects arranged at predetermined intervals along the vehicle route, the object display means, when displaying the plurality of objects, displays the plurality of objects while gradually reducing the size according to a reduction rate corresponding to an angle formed by an entry direction into the guiding branch point on the vehicle route and an exit direction from the guiding branch point on the vehicle route as the distance from the vehicle increases, and the superimposed image display device that increases the reduction rate as the angle becomes smaller.

2. The object display means, determines the size of the object at the position farthest from the vehicle according to the angle among the plurality of objects, and the superimposed image display device according to Claim 1, which gradually changes the size of the plurality of objects so that the objects at positions farther from the vehicle become smaller.

3. The object display means, when there is a guiding branch point within a predetermined distance ahead in the traveling direction of the vehicle, displays the guiding object that guides the vehicle route at the guiding branch point, and the superimposed image display device according to Claim 1 or Claim 2.

4. The object display means, when the angle is 90 degrees or less, displays the plurality of objects while reducing the size at a reduction rate corresponding to the angle, and when the angle is greater than 90 degrees, displays the plurality of objects while reducing the size at the reduction rate when the angle is 90 degrees, and the superimposed image display device according to any one of Claims 1 to 3.

Images